Recently, secondary batteries typified by lithium-ion batteries have been installed not only in portable devices such as mobile phones, and digital cameras, but also in electric bicycles, electric motor cycles and cars. Due to the various ways in which secondary batteries are used, battery weight reduction and increase design freedom have become current requirements. Film-packaged batteries that use a lightweight, easy to flexible film wrapping material have emerged as secondary batteries that can satisfy this demand. Further, for use requiring high power, battery packs that include a plurality of film-packaged batteries that are arranged in alternate layers are known.
In a battery pack, the occurrence of interlayer deviation among the film-packaged batteries increases the likelihood that the film-packaged battery will be damaged due to falling and impacts. Therefore, in a battery pack, it is preferable that film-packaged batteries are affixed to each other so as to prevent the occurrence of interlayer deviation. Patent Document 1 discloses a technique for affixing film-packaged batteries.
FIG. 1 is a perspective view showing a battery pack disclosed in Patent Document 1. In battery pack 100 shown in FIG. 1, the film-packaged batteries are each held in cell case 101. Cell case 101 is formed with conduits 102. Rod 103 is inserted into conduit 102. A nut is engaged at end 104 of rod 103. In this way, a plurality of cell cases 101 are fixed to rods 103, whereby the film-packaged batteries that are held in cell cases 101 are fixed to each other.